Named after its founder Osman Bey, the Ottomans were settled as a tribe in Sogut at the beginning of the great 600 hundred-year-old Empire.

OSMAN BEYwas born around 1258, the son of Ertugrul Gazi. In 1284 the Anatolian Seldjuk Sultan recognised Osman Bey as chief of the tribe. At the same time Anatolian Seldjuks were in the decline period and could not resist the attacks of Ilhanlis, Cengis Khans sons in Iran. This tragic situation held the people and tribes in Anatolia in a very chaotic and unstablemood. Anatolian Seldjukian Sultan, Giyaseddin Mesut II was in confidence with Osman Bey by positioning him as the ruler of the border tribe.

Byzantium was bored with struggles for the throne and being attacked by the Balkan princes and kings. The Greek Beys named as "Tekfurs" were not obedient to the Empire and the habitants were unhappy with high taxes. Osman Bey used this poor Byzantine condition and invaded the Greek Tekhfurs' cities of Karacahisar, Bilecik,Yarhisar and Inegol . On the other hand, the success of Osman encouraged Anatolian Seldjuk Sultan, Alaaddin III. He gave the cities Inonu and Eskisehir under the rule of Osman in 1289. When Alaaddin III was taken to Iran and killed by the Ilhanli Sultan Mahmut Gazan Han, the lack of authority in Anatolian Seldjuk caused the Ottomans independence in 1300 and Osman Bey coined his money.

In 1301, Yenisehir and Kopruhisar were conquered and Byzantine Yenisehir became the Ottoman's capital. The progress of Osman Bey in order to create a powerful state, made Tekhfurs and Byzantine Empire join forces against him. Tekhfurs of Bursa, Orhaneli and Kestel attacked the Ottomans at "Koyunhisar" in 1302 which was known as the first war between Byzantines and the Ottomans ended with the victory of the Ottomans. Bursa was surrounded step by step after the battle. The city was given by its tekhfur in 1326 to Orhan Bey , the son of Osman Bey.